The Mineralogical and Chemical Composition of the Strongly Magnetic Egyptian Black Sand Altered Ilmenite

The Egyptian black sand contains several types of altered ilmenite grains which have various magnetic susceptibility values, ranging from the strongly paramagnetic, such as ilmenite, to non-magnetic, rutile grains. relatively higher mass susceptibility, separated at 0.1, 0.2, 0.25, and 0.35 A using Frantz isodynamic separator, were investigated. Both brown investigated binocular microscope Cameca SX-100 microprobe. Most analyzed spots are composed mainly pseudorutile (psr) leached (lpsr), with contents TiO2 Fe2O3 between 56.76 78.09% 37.98 12.16%, respectively. Ti/(Ti+Fe) ratio ranges 0.59 0.85. chemical formula range psr-lpsr is Fe2.07-0.54Ti3O9-4.68(OH)0-4.32. lowest cationic iron content lpsr phase 0.5 a corresponding molecular Fe0.5Ti3O4.5(OH)4.5. In detected spots, Fe2+ 0 2.46, while Fe3+ 0.17 1.94. 0.51 0.6, Fe/Ti 0.91 0.67. Considering Fe3Ti3O9, formulas composition Fe2.72-2.02Ti3O9 minimum value total being equal 2.02. Some contained inclusions may be responsible for acquired characteristics some powdered X-ray diffraction patterns different before after heating 1100 oC one hour. hexagonal psr/lpsr structure more unstable than tetragonal structure. According calculations alteration phases, much lower that previously reported. Also, during process, mechanism changed in region 68-70 wt % TiO2. Then, late stages, does not suddenly collapse but gradually produces other associated mineral phases.